A162527 Numbers k whose largest divisor <= sqrt(k) equals 7.

49, 56, 63, 70, 77, 84, 91, 98, 105, 119, 133, 147, 161, 175, 203, 217, 245, 259, 287, 301, 329, 343, 371, 413, 427, 469, 497, 511, 553, 581, 623, 679, 707, 721, 749, 763, 791, 889, 917, 959, 973, 1043, 1057, 1099, 1141, 1169, 1211, 1253, 1267, 1337, 1351

Offset: 1

Author

Omar E. Pol, Jul 05 2009

Keywords

• easy
• nonn

Comments

See A161344 for more information.

Links

• Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A033676, A008578, A161344, A161345, A161424, A161835, A162526, A162528, A162529, A162530, A162531, A162532.

Programs

Maple

A033676 := proc(n) local dvs; dvs := sort(convert(numtheory[divisors](n),list)) ; op(floor((nops(dvs)+1)/2) ,dvs) ; end: for n from 1 to 2000 do if A033676(n) = 7 then printf("%d,",n) ; fi; od: # R. J. Mathar, Jul 13 2009

Mathematica

ld = 7;
selQ[n_] := AllTrue[Divisors[n], # <= ld || #^2 > n&];
Select[Range[ld, 200] ld, selQ] (* Jean-François Alcover, Apr 14 2020 *)
ld7Q[n_]:=Select[Divisors[n],#<=Sqrt[n]&][[-1]]==7; Select[Range[1400],ld7Q] (* Harvey P. Dale, Jan 13 2023 *)

Formula

Numbers k such that A033676(k)=7.

Extensions

More terms from R. J. Mathar, Jul 13 2009